1. Technical Field
The present invention relates to a disk chucking device.
2. Description of the Related Art
Generally, a disk driving device includes a disk chucking device for loading or unloading a disk and a spindle motor for rotating the disk, which is loaded by the disk chucking device, at a certain speed.
An important consideration for such disk driving device is a perfect alignment of the center of the disk chucking device and the rotational center of the disk mounted on the chucking device. If the center of the disk chucking device and the rotational center of the disk are not properly aligned, the high-speed rotation of the disk may further deviate the centers, causing vibration and noise.
FIG. 1 is a cross sectional view illustrating a disk driving device 10 according to the related art. As shown in FIG. 1, the disk driving device 10 has recently become much thinner, in response to a trend toward smaller sizes. Especially to reduce the overall thickness of a spindle motor 10, a shelf 14 is formed in the middle of a rotor case 12 so that space for holding the top portion of a bearing 16 is provided in the middle of the rotor case 12, and the portion facing a stator 18 is lowered.
FIG. 2 is a bottom view illustrating a disk chunking device 20 according to the related art. As shown in FIG. 2, a coil spring 24, which supports a chuck pin 22 elastically, is disposed in the radial direction of the conventional disk chunking device 20.
Accordingly, the disk chucking device 20 being coupled on top of the rotor case 12 may not have enough length, which will hereinafter be cited within the description as ‘L’, to accommodate the coil spring 24 because of the shelf 14 inside the disk chucking device 20. If the length of the coil spring 24 is not enough, the coil spring 24 may not have constant force against the same displacement.
Therefore, the chuck pin 22 may not be able to support the inner circumference of the disk with a constant force, misaligning the center of the disk chucking device 20 and the rotational center of the disk. If these centers are not properly aligned, a pick-up unit may not be able to write and/or read information accurately.